Tao-ming Cheng

An effective simulation mechanism for construction operations

Abstract Construction project planners have used computer simulation to predict the performance of the construction operation in terms of process flows and resource selection for decades. Traditionally, however, to find the best resource utilization of the construction operation, all possible resource combinations should be tested within the simulation process. That is, an exhaustive enumeration of resource combinations should be conducted, which is not economic if the possible resource combinations increase explosively. Therefore, simulation is not considered as an optimization technique. Genetic Algorithms (GA), developed by John Holland in 1975, has been widely applied to different disciplines of research for solving the optimization problems. GA is also known for its flexibility in hybridizing with other methodologies to obtain better solutions of the simulation systems. This paper presents a new mechanism that integrates simulation with GA to find the best resource combination for the construction operation. Results show that the new simulation mechanism can effectively locate the optimal resource combination for the construction operation and enhance the optimization capability of the construction simulation. In addition, a user-friendly computer simulation system—Genetic Algorithms with Construction Operation Simulation Tool (GACOST) was developed to provide the construction planner an efficient means of analyzing and optimizing the construction operation.

Optimizing the Schedule of Dispatching Earthmoving Trucks through Genetic Algorithms and Simulation

AbstractMost construction projects involve earthmoving operations. Careful management of trucks to perform these operations is considered crucial by earthwork contractors in Taiwan. A mechanism is described that optimizes the management of the truck fleets of earthwork contractors. The proposed model integrates a discrete event simulation technique and genetic algorithms (GAs) to minimize the duration of earthmoving operations. The discrete simulation model is applied to simulate earthmoving operations and generate schedules for dispatching various trucks, and the GAs are used as a filter to screen out schedules that require long trips. Examples prove that the proposed model can determine near-optimal solutions efficiently. In addition, a user-friendly computer program is developed so that earthwork contractors can plan the dispatch schedule of earthmoving trucks easily and effectively.

Construction Operation Simulation Tool - Cost

As a simulation methodology, CYCLONE has been widely used in the design and analysis of construction operation for over the last 20 years. MicroCYCLONE, as the implementation computer program of CYCLONE, had a great contribution in the promotion of CYCLONE. However, MicroCYCLONE is a DOS-based program and has not been improved since the existence of Windows-based computer operation system. This paper aims to introduce a new simulation program named as Construction Operation Simulation Tool (COST). It was developed using Visual Basic programming language based on CYCLONE methodology. COST not only updates the MicroCYCLONE program, but provides fuzzy data simulation function that facilitates the modeling uncertainty.

A Hybrid Optimization Mechanism Used to Generate Truck Fleet to Perform Earthmoving Operations

Most construction projects involve earth removal operations. Careful management of truck fleets to perform these operations is considered crucial by earthwork contractors in Taiwan. This paper presents a hybrid mechanism to optimize the management of the truck fleets of earthwork contractors. The authors use discrete event simulation models to represent earthmoving operations, and these models are used to simulate schedules for dispatching truck fleets. The authors then apply genetic algorithms to select the optimal schedules with the least amount of operational time. A theoretical example proves that the proposed mechanism can determine near-optimal solutions efficiently. Finally, the authors develop a user-friendly interface so that earthwork transportation companies can use the proposed mechanism easily and effectively.

Simulation with Fuzzy Durations

Traditional stochastic discrete event simulation method requires the users to fit the task duration data with an empirical probability function or a theoretical probability density function. This has limited the application of discrete event simulation techniques from research stage to construction practice due to the tedious data fitting tasks required for the construction operation planners lacking of statistical background. On the other hand, usually the activity duration estimated by practitioners contains some kind of vagueness caused by estimators subjective judgment. This type of vagueness may be more appropriate to be modeled by fuzzy numbers that can be assessed without data fitting. This paper proposes a new mechanism where fuzzy duration modeled by fuzzy numbers can be used in discrete event simulation. Consequently, the tedious data fitting tasks are eliminated but the uncertainty of task duration is still taken into account.

Simulation of NATM Tunneling Construction in Gravel Formation — Lessons Learned from Pakuashan Highway Tunnel Project in Taiwan

Construction processes are complex operations that include the use of equipment, materials, crews and geological conditions. Simulation can be used to study these processes in order to make competent decisions that will lower costs and shorten the duration of the project before it has started. Tunneling is a highly repetitive construction operation and simulation can be used to analyze the process. A model used to simulate the NATM tunneling construction operations for Pakuashan highway tunnel project is developed in this paper. This project is unique because of the soil conditions. A discrete event simulation methodology, CYCLONE, is used to build the operation model and simulate the tunneling processes. Statistical analysis indicates that duration of most tunneling operations can be modeled by Beta probability distribution. Results also show the model predicting the advancement rate of such tunneling project is accurate.

Dynamic survey of wind turbine vibrations

Six wind turbines were blown to the ground by the wind gust during the attack of Typhoon Soudelor in August 2015. Survey using unmanned aerial vehicle, UAV, found the collapsed wind turbines had been broken at the lower section of the supporting towers. The dynamic behavior of wind turbine systems is thus in need of attention. The vibration of rotor blades and supporting towers of two wind turbine systems have been measured remotely using IBIS, a microwave interferometer. However the frequency of the rotor blade can be analyzed only if the microwave measurements are taken as the wind turbine is parked and secured. Time-frequency analyses such as continuous wavelet transform and reassigned spectrograms are applied to the displacement signals obtained. A frequency of 0.44Hz exists in both turbines B and C at various operating conditions. Possible links between dynamic characteristics and structural integrity of wind turbine –tower systems is discussed.

A Study on Crew Performance Measurement by Using Heart Rate and Oxygen Consumption

To improve crew-level productivity, accurately measuring crew performance is the key issue. The accuracy of examining crew performance relies on the correctness and effectiveness of data collection. Some data collection techniques, such as productivity rating and five-minute rating, have their distinct advantages. However, they also have disadvantages in common. For example, the rating of effective work is based on observer’s personal judgment that could cause different results from person to person. To overcome this drawback, a study for exploring the possibility of using heart rate and oxygen consumption to monitor crew’s working conditions was conducted by the authors. Three types of work (effective work, essential contributory work, and ineffective work) were compared using participants’ heart rate and oxygen consumption at work. Participants, aged between 23 and 25, were involved in assembling formwork in a laboratory setting. Experimental results indicate that oxygen consumption at work can be used to effectively distinguish between effective work tasks, but is ineffective at distinguishing some contributory work and ineffective work items. Heart rate at work is ineffective for distinguishing between some effective work and contributory work tasks, or between contributory work and ineffective work items.

Correlation between intellectual capital and business performance of construction industry – an empirical study in Taiwan

ABSTRACT Researchers have sought to determine the correlation between intellectual capital and business performance to enable corporations to shape policy decisions that benefit business performance in the past two decades. Previous works have focused on information technology and biotechnology industries rather than on the construction industry. This research aims at developing a construction industry intellectual capital valuation model for managers of construction-related firms to make better decisions in managing intellectual capitals. An empirical study was conducted on the application of the proposed intellectual capital valuation model to four representative firms from the construction industry listed in Taiwans stock market. It is found from the results of the empirical study that the business performance of construction industry relies highly on intellectual capital. As a result, the managers of construction related-firms should emphasize more on accumulation of the intellectual assets in order to improve their business performance. Moreover, the empirical results also show that the traditionally conceived ‘capital- and labour-intensive’ construction industry is actually highly intellectually capitalized, with the average values of the MV/BV and Tobins q values significantly greater than 1.0 similar to that in the high-tech industries.

Remedial education for high-risk university freshmen – the case of a university of technology in Taiwan

Abstract Potential high-risk freshmen for three core courses (BasicMath, Calculus, and Computing) in the university were identified based on the “College Students’ Adjustment Check List (CSACL)” data available with the Student Development Centre in the Office of Students’ Affairs of the university. The study demonstrates that to ameliorate the problem of unpreparedness of freshmen, to check failure rates, and efficient use of limited resources, an effective remedial system could be developed by the combined inputs from the Office of Students’ Affairs, Computer Centre, Academic Affairs, and the Institutional Research. Our study corroborates the findings of other researchers that gender, teacher, department, high school performance, enrolment channel, and loads during remedial course influence the learning outcome. Also, it was found that the use of multi-evaluation approaches in different enrolment channels can attain higher retention rates.